1. Field of the Invention
The invention is directed to an improved fuel injection valve for internal combustion engines.
2. Description of the Prior Art
One fuel injection valve of the type with which this invention is concerned is, known from German Published, Nonexamined Patent Application DE 196 05 956, and has an extensively rotationally symmetrical valve base body, which tapers toward the combustion chamber, forming an annular shoulder and thus merges with a valve body shaft that protrudes as far as the inside of the combustion chamber. The valve base body is braced axially against a valve retaining body by means of a lock nut that engages the annular shoulder. The fuel injection valve is disposed in a receiving bore formed in the housing of an internal combustion engine, and the inside diameter of the receiving bore decreases toward the combustion chamber, forming a stop face. In the installed state of the fuel injection valve, the lock nut comes to rest on the stop face of the receiving bore. By a suitable tightening device, the fuel injection valve is pressed into the receiving bore toward the combustion chamber and is thus pressed with the lock nut against the stop face. The sealing off from the combustion chamber is assured by a sealing disk in the form of an annular disk, disposed between the stop face and the lock nut. A sealing disk of this kind, known from German Application DE 196 05 956, is thrust into the receiving bore over the valve body shaft before the fuel injection valve is installed, and is retained on the valve body shaft by radial bracing.
When the fuel injection valve is disassembled from the receiving bore and then reinstalled, the sealing disk has to be replaced to assure reliable sealing from the combustion chamber. In the fuel injection valves, the disadvantage then arises that the sealing disk can stay behind in the receiving bore when the fuel injection valve is dismantled. From there, the sealing disk can be removed only with major effort, possibly requiring special tools.
Since the fuel injection valve is usually manufactured as an outside vendor part, the known sealing disks also have the disadvantage that the sealing disk can loosen during shipping and be lost. Reinstalling the sealing disk when the internal combustion engine is equipped requires a further operation and entails additional costs.
Another difficulty arises in the known sealing disks because of the radial bracing of the sealing disk on the valve shaft. Inside the valve shaft, a valve member is guided in a bore, and both the valve member and the bore are manufactured extremely precisely and with only very close tolerances. Hence it cannot be precluded that some impairment of this guidance will occur from the radial forces exerted on the valve shaft. Imprecise guidance of the valve member can cause inexact injection performance and can finally lead to failure of the fuel injection valve.
The fuel injection valve of the invention for internal combustion engines[, as defined by the characteristics of the body of claim 1,] has the advantage over the prior art that the sealing disk is joined in captive fashion to the lock nut, and no forces are exerted on the valve body shaft.
According to our embodiment, the undercut of the outside wall of the annular heel is formed in a simple way by means of a conical design. Accordingly, in the non-installed state, the outside jacket face of the sealing disk is likewise embodied at least approximately conically, so that after the annular rib has been wedged into the undercut of the annular heel, the outside jacket face of the sealing disk is virtually cylindrical. The cone angle for both the annular heel and the sealing disk is from 4 to 10xc2x0, preferably approximately 5xc2x0.
After the fuel injection valve has been removed, a new sealing disk must be placed on the annular heel of the lock nut and wedged against it with a pulling tool. In an auto repair facility, however, such a tool may not necessarily be available. In a further advantageous feature, a further, encompassing lower annular rib is therefore formed on the side of the sealing disk toward the combustion chamber, and this annular rib is located substantially opposite the first annular rib, the one remote from the combustion chamber. When the fuel injection valve is braced against the stop face formed in the receiving bore, the lower annular rib is pressed toward the valve retaining body and as a result presses the first annular rib inward into the undercut, so that the sealing disk is solidly connected to the lock nut without requiring any additional tool. The next time the fuel injection valve is dismantled, the sealing disk, as in the case of assembly with the aid of a pulling tool, is removed along with the fuel injection valve from the receiving bore.
In a further advantageous feature, the sealing disk has a smaller diameter than the lock nut. This makes it possible with a screwing tool, such as a screwing nut to reach past the sealing disk and thus screw the lock nut against the valve retaining body. The installation of the sealing disk can be done either before or after the lock nut is screwed to the valve retaining body.
According to our embodiment, the sealing disk is made from a metal that is soft in comparison to the material of the valve body, so that durable deformation without major effort is possible even at room temperature. For this purpose, copper, a copper alloy, soft iron or an aluminum alloy is suitable.